Method of metal-drawing.



. H'. G. CARLSON. METHOD 0F METAL DRAWING. APPucATlou man ockr. 24. um nsuzwsn JAN. I4. |919.

Patented Feb. 25, 1919.

3 SHEETS-SHEET l.

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H. G. CARLSON.

METHOD 'or METAL DRAWING. APPLICATION FILED OCT. 24. 19|]- RENEWED IAN. r4'. 1919.

L9,3. Patented Feb. 25, 1919.y

3 SHEETS-SHEET Z.

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HJALMAR Gr. CARLSON, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO ROCIWOOD SPRINKLER COMPANY OF MASSACHUSETTS, CORPORATION OF MASSACHUSETTS.

METHOD or METALDnAwINe.

Specification of Letters Patent.

Patented Feb. 25, 1919.

Application led October 24, 1917, Serial No. 198,326. Renewed January 14, 1919. Serial No. 271,162.

To all whom t may concern.'

Be it known that I, HJALMAR G. CARLSON, a citizen of the United States, residing at Worcester` in the county of Worcester and State of Massachusetts, have invented a new and useful Method of Metal-Drawing, of which the following is a specification.

This invention is an improvement over my prior Patent No. 1,200,309, patented October 3, 1916, and relates, as that does, to a method of producing a hollow article of sheet metal such as a shell or booster casing which may be used for many purposes in accordance with its particularsize and sha-pe. A characteristic feature of the article, however, is that it varies in thickness from itsclosed end to its open end, being thicker at the open end, and cylindrical inside but conical outside. Also it may have in addition an integral enlargement at .its open end formed by a thickening process instead of being doubledover or creased, so tha-t it has no internal seam.

The vprincipal objects of this invention are to provide a method of producing an article such as above described, but of superior character and with the employment of comparatively little power, and particularly to provide means whereby by a simple drawing operation the interior of a shell-shaped 4article can be left in -a uniform and smooth condition` and an article finally shaped up -to the desired definite shape.

Reference is t0 be had to the accompanying drawings, in which- Figure l is a transverse sectional view of a die showing a plunger in the actof performing the firstv operation;

Fig. 2 is a similar view showing the second operation; l

Fig. 3 is a sectional viewjof a different form of die and a plunger showing the oper, ation of reducing the thickness of the end of the blank;

Figs. 4, 5 and 6 are views similar to Figs. l and 2 showing three other specific steps of the method as set forth in my above -men- .tioned patent.

Fig. 7 is a similar View sho-wing the first additional step of the new method;

Fig. 8 is a similar View showing the next lstep in which the stripping'- ofthe blank from the plunger also assists in shaping it;

Fig. 9 is a similar view showing the thickenmg of the edge; v l

patent is designed for the production of the shell having a cylindrical surface inside,

provided with a closed end and an open end,

and having the metal thicker at its open end than at i-ts closed en-d and growing so progressively from one end to the other.

I have discovered, however, that I can materially improve the product of that method, as well as reduce the amount of power required for it, by `adding a double operation. This consists in drawing the metal out on a conical plunger, larger at the end than at the top. This allows the thicken-ed top part of the blank to conform itself to the plunger.' Then the blank is stripped forcibly off the plunger which in itself further smooths the inside ofthe blank and shapes it to a true cylindrical form.

Referring now to the drawings,`the first step in the preferred process is to take a flat' blank and place it o-n top of a die 10 which has a perforation or opening 11 of a shape corresponding with the shape of thede sired article, in -this case circular. This .opening also is smaller than the diameter of Iedge of the blank so that this edge is slightly thickened.

The cup-shaped blank'v a having been produced in accordance' with the arrangement .shown in Fig. l, it is then placed in a second die 20 and forced through it by a cylindrical plunger 22. The blank a is produced having a further elongation and smaller diameter and its edge is thickenedA still fur-ther.

It is found in practice that this thickening .A

extends substantially 'from the open to the closed end of the blank so that the blank may be considered-as having a conical inner surface, although it is not a perfect cone.

-tO each other, as has been described, and' a with the plunger when the latter .series of blanks a2, a3, and a is obtained,

each one smaller and longer than the one from which it is made and thicker at its open edge. The dies and plungers operating on the blanks a2, a3, and a* are designated respectively 30, 40, 50 and 32, 42 and `52 all these plungers being shown as cylindrical.

At an intermediate point in this process, preferably 'after the operation shown in Fig. 2, and before that shown in Fig. 4, the closed end of the blank is flattened and thinned by subjecting the blank to pressure between a flat bottomed die 23 and a plunger also having a flat bottom. This plunger may be if desired made of exactly the same shape and size as the plunger 22 and may in fact be the same one as indicated.' If desired, the die 23 can be located just below the die 20 and receive the plunger and blank as soon as the latter is freed from the die 20 by passing entirely through it.

lt will be understood that the number of operations above described will depend upon thearticle being produced and the metal of which it is produced and that this method is not limited to any particular number of such operations. y f

After the blank has been brought to the condition shown at a4 in 'which it is of substantially the diameter and length' desired, the rough, thickened open end is squared o' by any desired means, and then it is put through the operation shown in Fig.,7. ln Fig. 7 it is shown as 'being forced into a die 53, |vvhich instead of having a cylindrical passage therethrough, is provided with a cavity having two cylindrical portions 54 and 56 and a double convex portion 55 of different sizes. The blank is forced into this die by a plunger 57 which is conical with the larger diameter at the end and it has a shoulder 58.

This die 54-55-56 is supported on a die bed 59 having a central hole intowhich the blank can be forced and supporting two stationary rods 60 having springs 61 that carry uponthem a stripping plate 62 supported by the springs. Nuts or other stops 63 are provided for preventing the rise of the stripping plate abo've a certain position. The stripping plate is provided Iwith/a stripper 64 through which the plunger 57 passes and which substantially Ifits the upper cylindrical non-working part of the plunger. This plunger is carried 'by a punch block 65 that reciprocates in a well known manner. It is to be noted that the plunger is vented by a perforation 66.

In operation the blank a4 is registered is in its highest position and can be held by the hand while the plunger comes down and takes the blank down through the' die 54, 55 and 56. The double convex part 55 of this die is the part that does the Work and is an 7 is to again thicken the metal at the top n and force it in against the conical plunger all along its surface leaving the blank a5 conical insideand cylindrical outside.

After the blank is thus formed up into the shape indicated at a5 the plunger is drawn back through the same die surface 55. It will be seen now that 'by giving this die sur-` face its double curved shape a true drawing operation can be performed as the plunger is .withdrawn lnasmuch as the blank has been forced back against the conical plunger in the previous operation the pluriger will securely hold the blank while it is being drawn up through this die and the die will tend further to smooth its surface. Vhen the plunger is withdrawn to the position indicated in Fig. 8 the edge of the blank comes against the stripper 64 and then the plunger is withdrawn from the blank by force. T his necessarily brings the inside 'of the blank to a true cylindrical shape and forces the metal out on the previously smoothed outside into a conical shape again.

The withdrawal of the plunger 57 constitutes another step of the process because the gradually thickening plunger necessarily forces the metal out and smooths the inside leaving it truly cylindrical. This again leaves the shell a6 conical outside.

The neXt operation shown in Figs. 9 and 10 consists in forcing the blank into a die 70 having a conical surface 7l and an enlarged cylindrical surface 72. This is done by means of a plunger 73 of cylindrical form throughout. The die 70 is supported in a stationary die bed and above it is supported by springs 74 on rods 75 a pla-te 76 which carries a die 77 through which the plunger 7 3 is adapted to be forced. This plunger 73 has a shoulder 7 8 at its topy on which rests a plate 79 located in a well in a die head 80 and pressed down by a heavy spring 81. This gives the plunger power of motion independent of the die head 80 which is operated positively. The lower part of the die 77 is cylindrical to fit in the cylindrical surface 72 of the die. The operation of this mechanism is as follows When the punch is moved up and the die 77 has followed it on account ofthe action of the springs 74 the blank a previously described is put on the plunger-as just described. Then the die head 8O comes down and forces the blank a6 into the conical reycess71 which exactly lits it. The outside of the plunger 7 3 also exactly lits the inside cylindrical surface of the blank a6. Consequently below the enlargement 72 of the die no shaping operation takes place here, but

the plunger 7 3 is held down byheavy spring pressure due to the spring 81 and thus premove down the projection 82 on the die head forces the plate 76 down and the die 77 into the opening 72` and tends to consolidate the shouldered end edge of the blank and finally brings it intothe form a7 shown in Fig. 10.

It is to be noted that the die 70 is provided with a vent 84 at the bottom and with aside vent 85 at the top. Also that the plunger is provided with a vent 86 connected vwith a longitudinal vent 87 to allow the air to escape. Thisis an important matter because the parts it so tightly that otherwise the air originally present on both sides of the edge. of the blank would tend to cause irregularities in the product or split the dies. By this venting action both diiiculties are entirely avoided and the blank comes out in the form shown at a7. By this series of operations a `blank is produced which is not only cylindrical and coni-cal as stated, butin which these cylindrical and conical `surfaces are smooth and perfect and the amount of power required even in my above mentioned partent to produce an inferior article is materially reduced, while the possibility of splitting the dies is entirely removed and the expense of the machine which has been thought necessary heretofore is reduced to a verysmall `maximum- The result of this operation is to finish the shell a7 'so as to retain its complete true cylindrical inner surface, give it a true conical outer surface,'and shape its enlarged cylindrical shoulder at the top having a square end. Upon being removed from this die and plunger, the shell is ready Yfor any machining operations such as providing the screw-threads, on the shoulder of the shell 4a7.

In this way an article is secured having a maximum'strength and of a maximum degree of perfection throughout, and yet the method of producing it is soextremely eX- peditious tha-twhen a large numberof articles are to be produced it can be done in a most inexpensive manner and without the use `of much power. l

Although I have illustrated and described a certain number and sequence of steps and shown the method as applied to the production of a specified article, l am aware of the fact that the invention is not limited to these respects and therefore I do not wish to be so limited except as set forth in the claims.

Having described the invention what I claim is y .1. The method vof ,drawing man which comprises forcing a blank through a die by means o-f a plunger larger at its tip 'than at i'tsbutt end, thus leaving a space between the die and plunger around they latter greater than the `original thickness of the metal, whereby the metal throughout its length will buckle upon itself Aand thicken but will be Shaped and drawn out between the die and v7.o

plunger.

' 2. The method of drawing out"and upsetting a cup-shaped blank, which comprises forcing the cup-shaped blank through a die by means of a conical plunger so as to cause the metal to buckle yon itself and thicken,

causing the metal to remain in contact with and be shaped' by the plunger all along theA same so as to draw the thickened metal out to a thickness greater than its original thick! lfrom end to end.

4. The method of drawing metal which consists in placing a cup-shaped blank against a die having a circular passage therethrough 'smaller than the diameter of said blank, forcin a plunger into the blank so as to bear on the inside of its closed end to force the blank through the die, for the purpose of elongating the blank, reducing yits `outside diameter and thickeningv its open edge, and shaping the interior of the blank by means of the tip of the plunger.

5. The method of drawing metal which consists in forcing a blank into a die having av passage therethrough smaller than the blank by means of a cylindrical plunger having substantially the same shape as said.

passage but small enough to permit the edge of the blank `to thicken when in the die, and thereafter subjecting the said blank to a further drawing operation in a die smaller than the blank asv it comes out of the first die to permit the edge of theblank to thicken,

whereby the blank is formed f of uniform outside shape from end to end but its inside diameter at the closed end is greater than it is at its open end, and stripping the plunger from the blank, thus shaping it to `uniformV inside the diameter at its open end.. i

6. The method of drawing metal which consists in forming by drawing operations a cup-shaped blank of cylindrical- ,external form vand roughly conical inside with a closed relatively thin end, forcing it through a die of smaller diameter than the blank by means of a plunger large enough at its 'tip to fill the blank as drawn through said die and growing progressively smaller toward its butt end to furnish room to receive the thickened metal of the blank, and then stripping the plunger from theblank to shape and smooth 'its inside surface.

7. The method of drawing metal which consists in drawing out a cup-shaped blank on a plunger to a form in which it is cylindrical outside and conical inside with its open end having a smaller inside diameter than its closed end and then bringing its interior to a uniform diameter.

8. rIhe method of drawing metal which consists in drawing out a cup-shaped blank on a plunger to a form in which it is cylindrical outside and conical inside with its open end havin a smaller inside diameter and a greater tiickness of metal than its closed end, and-'then drawing the plunger out through the small end to bring the inside to a. cylindrical form with its open end thicker than its closed end.

9. The method of drawing metal which consists in drawing out a cup-shaped blank on a plunger so as to force the metal against the plunger substantially throughout the length of the blank thus bringing the blank to a form in which it is cylindrical outside and conical inside with its open end having a smaller inside diameter than its closed end, then drawingthe plunger out through the small end to bring the inside toa cylindrical form, but leaving the edge of the blank larger than the main part, then holding the inside and outside surfaces of the blank under high pressure throughout its main partl to prevent any change in shape and compressing said larger edge.

vl0. The method of drawing metal which consists in drawing out a cup-shaped blank on a plunger so as to force the metal against the plunger substantiall throughout the length of the blank thus ringing the blank to a form in which it is cylindrical outside and conical inside with its open end having end, and then drawing through the small end to bring theinside-to.

a smaller inside diameter than its closed the plunger out a cylindrical form,'but leaving the edge-of the blank of larger diameter Athan the rest of it, then forcing it into a diehaving the exact shape and size of the blank: by means of 'a plunger fitting fthe interior ofthe blank,"

holding the plunger in position under pressure and compressing the edge of the blank.

ll. The method of drawing metal which consists in drawing out a cup-shaped blank onY a plunger so as to force the metal against the plunger substantially throughout the length of the blank thus bringin the blank to a form in which it is cylindrical outside and conical inside with its open end having a smaller inside diameter than its lclosed end, then drawing the plunger out through the small end to bring the inside to a cylindrical form, but leaving the edge of the blank larger than the main part, then holding the inside and outside surfaces of the blank under high pressure throughout `its main part to prevent any change in shape, compressing said larger edge, and venting the external surfaces ofthe blank.

l2. The method 4of drawing metal which consists in drawing out a blank to a cylindrical form outside and conical inside, its open end having a smaller inside diameter and of greater thickness than its closed end, then drawing the plunger on which it is made out through the smaller end to bring the inside to a cylindrical form, but leaving the edge of the blanklarger and thicker than the'main part, then holding 'the inside and outside surfaces of the blank under pressure throughout its main part to prevent any change in shape, and longitudinally compressing said larger edge.

13. The' combination with a circular die, of a plunger coperating therewith of conical form throughout its operative length with its large end at the tip.

14:. The combination with a female die, of a plunger cooperating therewith having its large end at the tip, said die having a continuous double convex curve constituting the operating surface.

l5. The combination with a Afemale die having a double curved operating surface,

of a spring supported stripping plate, and a positivelyoperated plunger largest at its tip and gradually growing smaller toward its other end and passing through said strip- 'i ping p'late into said die. g

In testimony whereof I have hereunto -affixedmy signature.

' TIUALMAR e. CARLSON. 

